I worked for the Rock Cats for a couple of seasons, this is huge for the team. What it really came down to is that the stadium was too small for what the team was attracting. They continue to break attendance records every year, and they have become limited by their stadium capacity.
Facility wise, NB Stadium isn't that great for being less than 20 years old. Not a bad seat in the house, but that's about all it has going for it for the fans, front office, & players. Also, location wise this is a huge upgrade. There is literally nothing around NB Stadium. As someone else mentioned its between NBHS and a park. Although it is conveniently near Route 9, it's a traffic nightmare both pre & post game since there is only 1 way in and 1 way out.
As long as they keep prices relatively the same, I think attendance will improve even more. It will be so much easier for business events on weekdays (people can walk from their office--nothing like a summer rooftop party at the game with a few kegs) and on weekends for families it will just be a better destination with a brand new stadium/location. Grab some dinner before a Saturday night game, what else is better than that during the summer?
Huge win for Hartford & its local businesses, huge loss for NB but there really isn't anything around it that will be negatively impacted.